Birth Date in the Raiser's Edge allows the Age field on the constituent record to be calculated based on the month, day and year.  However, the age field should not exceed 3 digits (i.e. a person cannot be more than 999 years old).  If the year is entered incorrectly (e.g. a person enters 950 instead of 1950), it may not trigger the error on the record itself, but it will prevent event registrations from being processed.  This field cannot be edited to extend the field length.  To resolve this error so the transaction can be processed:

1.  In Raiser's Edge, open the constituent record for each participant in the transaction
2.  Edit the birth date to a valid date.
3.  Click Save and Close.  The Age will automatically recalculate to be 3 characters or less.  
4.  Go back to the plugin and process the transaction.  The error should be resolved.